Destination.Allocate(dstWidth, dstHeight);

Source.RenderToTIEBitmapEx(Destination,
  0, 0, dstWidth, dstHeight,
  srcX, srcY, srcWidth, srcHeight,
  False, 255, Resample
);

Source.CopyRectTo(Destination,
  0, 0, 0, 0, dstWidth, dstHeight
);

procedure TForm1.Button1Click(Sender: TObject);
const
  srcX = 10;
  srcY = 10;
  dstWidth  = 300;
  dstHeight = 300;
  srcWidth  = 200;
  srcHeight = 200;
  Resample = rfWICLinear;
begin
  ImageEnView2.IEBitmap.Allocate(dstWidth, dstHeight);

  ImageEnView1.IEBitmap.RenderToTIEBitmapEx(ImageEnView2.IEBitmap,
    0, 0, dstWidth, dstHeight,
    srcX, srcY, srcWidth, srcHeight,
    False, 255, Resample );

  ImageEnView2.Update();
end;